\section{Tests.}

A series of statical tests were performed to check the proper functioning of
the system \href{http://www.youtube.com/watch?v=v-CarBSXGhg}{(see video)}.

Then a series of test flights were performed. The sequence o photographs below
shows the preparation for the first test flight of the altimeter.  For this
first flight, a cartridge full of ferrite was attached to drogue ejection
system, to provide a visual feedback of the event.

\begin{center}
\begin{tabular}{ccc}

\scalebox{0.15}{\includegraphics{01_altimetro_vista_general.jpg}} &
\scalebox{0.15}{\includegraphics{02_altimetro_carga_trazadora_en_apogeo.jpg}} &
\scalebox{0.150}{\includegraphics{03_altimetro_aislacion_inferior.jpg}} \\
General view & Trace charge & Low insulation \\

\scalebox{0.15}{\includegraphics{04_altimetro_soporte_prfv_vista_inferior.jpg}} &
\scalebox{0.15}{\includegraphics{05_altimetro_soporte_prfv_vista_lado_bateria.jpg}} &
\scalebox{0.15}{\includegraphics{06_altimetro_soporte_prfv_vista_lateral.jpg}} \\
Low view & Battery view & Lateral view \\

\scalebox{0.15}{\includegraphics{07_bahia_de_carga.jpg}} &
\scalebox{0.15}{\includegraphics{08_altimetro_en_bahia_de_carga.jpg}} &
\scalebox{0.15}{\includegraphics{09_bahia_de_carga_en_cohete.jpg}} \\
Payload bay & Altimeter in payload bay & Payload bay in the rocket \\

 & \scalebox{0.15}{\includegraphics{10_listo_para_ensayo.jpg}} & \\
 & \href{http://www.youtube.com/watch?v=AshBXy-GXK8}{Ready for the first fly (video)} & \\

\end{tabular}
\end{center}

Tests on version 2.0 were performed under the following conditions:

\begin{itemize}
\item MPLAB as simulation environment.
\item Circuitry mounted on protoboard and barometric mini-chamber:
\begin{center}
  \begin{tabular}{cc}
    Open chamber & Closed chamber \\
    \scalebox{0.10}{\includegraphics{camara_abierta.jpg}} & 
    \scalebox{0.10}{\includegraphics{camara_cerrada.jpg}}
  \end{tabular}
\end{center}
\item Comparison of Altimetro alpha with a comercial altimeter Perfectflite miniALT/WD.
\end{itemize}

Having no adequate metrological instruments at hand, a comercial Perfecflite
altimeter was used to check the performance of our altimeter.

Several comparative tests were performed using a barometric mini-chamber.
The next table shows the result of 4 tests performed:

\begin{center}
\scalebox{0.70}{\includegraphics{tabla_ensayos.png}}
\end{center}

The video of the last test can be downloded from
\href{http://www.youtube.com/watch?v=LtZBj-b0oJI}{\textbf{HERE}}

In the video it is shown that the \textbf{$\alpha$ Altimeter} is connected to
two small car lamps covered with a blue lid, and the Perfectfilte (PF) with
two unlidded lamps.

When air is removed from the barometric chamber, the \textbf{$\alpha$
  Altimeter} detects lift off and the led flashes. When ``apogee'' is reached, the
igniters of the \textbf{$\alpha$ Altimeter} (down, right) are lit, and
immediately the Perfectflite ignitor is lit (up, right).  After approximately
10 seconds both altimeters simultaneously detect "landing".

At that moment the \textbf{$\alpha$ Altimeter} turns off both lamps. Both
altimeters start reporting the ``altitude'' reached.

In the case of Perfectflite, it reports 1800 feet (549m) while
\textbf{$\alpha$ Altimeter} reports 553 m, with less than 1\% difference
between them (4m).

Similar behaviour was observed on the other tests.

The method used to detect landing is completely different in both
altimeters.

The Perfectflite altimeter asumes landing has happend when two conditions are
met:

\begin{enumerate}
\item An altitude of at least 300 feet (91 m) above ground level is reached.
\item The descent rate is less than 4 feet/s.
\end{enumerate}

On the \textbf{$\alpha$ Altimeter}, landing is assumed after
pressure remains constant for at least 10 seconds.

The next image shows a unit of the altimeter completely assembled and ready for testing:

\scalebox{0.25}{\includegraphics{alfa_34_listo_para_primer_ensayo.jpg}}